Portable multisensor for measurement of the thermo hygrometric variables in the determination of the comfort conditions

A new multisensor for three of the four ambient variables of thermo hygrometric comfort has been realized, based upon the thermal and fluid dynamic behaviour of a flat heated surface, in transient state. The sensor is made up of a glass substrate with a gold layer deposited on it, used both as heater for current flow though it and as temperature sensor. Air temperature is measured while current is so low to don't produce self heating, while during the first seconds of heating convection heat transfer coefficient is evaluated, and from it air velocity is measured. Finally, mean radiant temperature is measured from the difference between the heat transfer coefficient results of the two part of the sensor: one blackened and another bright as after gold deposition. Test showed good accuracy in determination of the temperature and the other quantities.